Rising temperatures pose a threat to the stability of climate regulation by carbon metabolism in subtropical forests. Although the effects of temperature on leaf carbon metabolism traits in sun-exposed leaves are well understood, there is limited knowledge about its impacts on shade leaves and the implications for ecosystem–climate feedbacks. In this study, we measured temperature response curves of photosynthesis and respiration for 62 woody species in summer (including both evergreen and deciduous species) and 20 evergreen species in winter. The aim was to uncover the temperature dependence of carbon metabolism in both sun and shade leaves in subtropical forests. Our findings reveal that shade had no significant effects on the mean optimum photosynthetic temperatures (T_Opt) or temperature range (T₉₀). However, there were decreases observed in mean stomatal conductance, mean area-based photosynthetic rates at T_Opt and 25 °C, as well as mean area-based dark respiration rates at 25 °C in both evergreen and deciduous species. Moreover, the respiration–temperature sensitivity (Q₁₀) of sun leaves was higher than that of shade leaves in winter, with the reverse being true in summer. Leaf economics spectrum traits, such as leaf mass per area, and leaf concentration of nitrogen and phosphorus across species, proved to be good predictors of T_Opt, T₉₀, mass-based photosynthetic rate at T_Opt, and mass-based photosynthetic and respiration rate at 25 °C. However, Q₁₀ was poorly predicted by these leaf economics spectrum traits except for shade leaves in winter. Our results suggest that model estimates of carbon metabolism in multilayered subtropical forest canopies do not necessitate independent parameterization of T₉₀ and T_Opt temperature responses in sun and shade leaves. Nevertheless, a deeper understanding and quantification of canopy variations in Q₁₀ responses to temperature are necessary to confirm the generality of temperature–carbon metabolism trait responses and enhance ecosystem model estimates of carbon dynamics under future climate warming.

气温上升对亚热带森林碳代谢调节气候的稳定性构成威胁。尽管温度对暴露在阳光下的叶子中碳代谢特征的影响已得到充分了解，但对其对遮荫叶子的影响以及对生态系统-气候反馈的影响的了解有限。在本研究中，我们测量了 62 种木本植物（包括常绿和落叶植物）夏季和 20 种常绿植物冬季光合作用和呼吸的温度响应曲线。目的是揭示亚热带森林阳光和遮荫叶子碳代谢的温度依赖性。我们的研究结果表明，遮荫对平均最佳光合温度（ T _Opt）或温度范围（T ₉₀ ）没有显着影响。然而，在常绿和落叶物种中，观察到平均气孔导度、T _Opt和 25 °C 时基于面积的平均光合速率以及 25 °C 时基于面积的平均暗呼吸速率下降。此外，冬季向阳叶的呼吸温度敏感性（Q ₁₀）高于遮荫叶，夏季则相反。叶子经济谱特征，例如单位面积的叶子质量以及不同物种的叶子氮和磷浓度，被证明是T _Opt、T _{90 、} T _Opt下基于质量的光合速率以及基于质量的光合作用和呼吸的良好预测因子25°C 时的速率。然而，除冬季遮荫叶外，这些叶子经济谱性状对Q _{10的预测效果不佳。}我们的结果表明，多层亚热带森林冠层碳代谢的模型估计不需要对阳光和遮荫叶子的T ₉₀和T _Opt温度响应进行独立参数化。然而，有必要更深入地了解和量化冠层Q _{10对温度的响应变化，以确认温度-碳代谢特征响应的普遍性，并增强未来气候变暖下碳动态的生态系统模型估计。}